TWI677720B - Optical image sensing device - Google Patents

Abstract

An optical image sensing device includes a light source, a first polarizing plate, a sensing element, an optical structure layer, and a light guide module. The first polarizer and the optical structure layer are located on the sensing element. The first polarizing plate is adapted to pass light having a first polarization direction. The optical structure layer has a plurality of oblique through holes, and each of the oblique through holes and the sensing element has a first angle. The light guide module has a first surface, wherein the first light beam provided by the light source is reflected by the first surface and transmitted to the first polarizer. The first light beam incident on the first surface at a first included angle is modulated to have a second polarization direction, and the second polarization direction is orthogonal to the first polarization direction.

Description

Optical image sensing device

The present invention relates to an image sensing device, and in particular to an optical image sensing device.

The traditional imaging optical fingerprint sensor is a fingerprint collection device composed of a light source, a diaphragm, and a sensing element. The principle is to transmit the light beam provided by the light source to the finger pressing the cymbal, and then use the peaks and troughs of the fingerprint to interfere and destroy the light beam to obtain the relevant fingerprint image information. Image capture and output. Because this optical acquisition method does not touch the chip itself, that is, the fingerprint pressing part is composed of optical elements such as acrylic or glass, the optical fingerprint sensor has the advantages of low cost and durability, and can be widely used. It is used in various devices.

Another conventional optical fingerprint sensor is a vertical through hole disposed on the sensing element to receive fingerprint image information. However, the sensing element of the optical fingerprint sensor receives a fingerprint image At the same time as the information, unwanted background noise is also received, resulting in a poor Signal to Noise Ratio (SNR) of the fingerprint image information.

The invention provides an optical image sensing device, which can generate an image with good quality.

The optical image sensing device of the present invention includes a light source, a first polarizer, a sensing element, an optical structure layer, and a light guide module. The light source is adapted to provide a plurality of light beams, and the light beams include a first light beam. The first polarizing plate is adapted to pass light having a first polarization direction. The sensing element has a sensing surface, wherein the first polarizer is located on the sensing element. The optical structure layer is located between the sensing element and the first polarizer, wherein the optical structure layer has a plurality of oblique through holes, and each of the oblique through holes and a normal vector of the sensing surface has a first angle. The light guide module is located on the transmission path of the first light beam. The light guide module has a first surface. The first light beam is reflected by the first surface and transmitted to the first polarizer, and is incident on the first surface at a first angle. The first light beam is modulated to have a second polarization direction, and the second polarization direction is orthogonal to the first polarization direction.

In an embodiment of the present invention, the light guide module includes a second polarizer, a cover, and a light guide layer. The second polarizer is located on the transmission path of the first light beam, and a surface of the second polarizer facing the first polarizer is the first surface. The cover is located on the second polarizer. The light guide layer is located between the cover and the second polarizer.

In an embodiment of the present invention, the above-mentioned light beams further include a second light beam. The second light beam is transmitted to an object contacting the cover body and then reflected, and the sensing element recognizes the second light beam reflected by the object. .

In one embodiment of the present invention, the second polarizer is a circular polarizer.

In an embodiment of the present invention, after the second light beam is modulated by the second polarizer, a part of the second light beam transmitted to the first polarizer has a first polarization direction and is transmitted to the first polarizer. The other part of the second light beam has a second polarization direction.

In an embodiment of the present invention, the second polarizer is a linear polarizer.

In an embodiment of the present invention, after the second light beam is modulated by the second polarizer, the second light beam transmitted to the first polarizer has a first polarization direction.

In an embodiment of the present invention, the first included angle is equal to the Brewster angle of the first light beam incident on the first surface.

Based on the above, the optical image sensing device according to the embodiment of the present invention uses the configuration of the oblique through hole and the light guide module so that the light with noise can be incident on the sensing element obliquely only at a specific incident angle. The light above and having this specific incident angle is linearly polarized light having a specific polarization direction. In this way, the optical image sensing device can filter the light with noise in this part by the configuration of the first polarizer, thereby improving the signal-to-noise ratio of the image information, and can produce an image with good quality.

In order to make the above features and advantages of the present invention more comprehensible, embodiments are hereinafter described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of an optical image sensing device according to an embodiment of the invention. Referring to FIG. 1, the optical image sensing device 100 of this embodiment includes a light source 110, a light guide module 120, a first polarizing plate 130, an optical structure layer 140, and a sensing element 150. For example, in this embodiment, the light source 110 may include a substrate 111, a plurality of light-emitting elements 112, and a protective layer 113. The light-emitting element 112 is located on the substrate 111 and is located between the substrate 111 and the protective layer 113. For example, in this embodiment, the material of the substrate 111 may be glass or polyimide film, and the light-emitting element 112 may be an organic light-emitting diode (OLED), but The invention is not limited thereto. On the other hand, as shown in FIG. 1, in this embodiment, the protective layer 113 is located between the light emitting element 112 and the light guide module 120 to block outside water and oxygen from penetrating. For example, in this embodiment, the protective layer 113 may be glass, an encapsulation material, or other encapsulation films suitable for using a film encapsulation process, and the present invention is not limited thereto. In addition, as shown in FIG. 1, in this embodiment, the light source 110 may optionally include a packaging frame 114 located at an edge region of the light source and surrounding a plurality of light-emitting elements 112 to block external moisture and oxygen from penetrating. .

For example, in this embodiment, the light source 110 is adapted to provide a plurality of light beams L. Specifically, as shown in FIG. 1, in this embodiment, the light beam L provided by the light source 110 may include a first light beam L1 and a second light beam L2. In addition, as shown in FIG. 1, in this embodiment, there is a gap VD between the adjacent light emitting elements 112, which is suitable for allowing the first light beam L1 reflected by the internal optical component in the optical image sensing device 100. With the second light beam L2. More specifically, as shown in FIG. 1, in this embodiment, the light guide module 120 is located on a transmission path of the first light beam L1. The light guide module 120 has a first surface S1, and the first surface S1 faces the first polarizing plate 130. For example, in this embodiment, the light guide module 120 includes a second polarizer 121 and a cover 122, wherein a surface of the second polarizer 121 facing the first polarizer 130 is the first surface S1. Moreover, as shown in FIG. 1, in this embodiment, the cover body 122 is located on the second polarizing plate 121. For example, in this embodiment, the material of the cover 122 may be glass, but the invention is not limited thereto.

Further, as shown in FIG. 1, in this embodiment, the second polarizing plate 121 is located on the transmission path of the first light beam L1, and the first light beam L1 is transmitted to the first polarization after being reflected by the first surface S1. Tablet 130. Moreover, when light is reflected in a non-metallic medium, the reflected light will have a polarization characteristic, that is, when the incident angle of the light is equal to the Brewster angle θb of the interface, the reflected light will be 100% linearly polarized light. Therefore, in this embodiment, the first light beam L1 incident on the first surface S1 at the Brewster angle θb of the first surface S1 can be modulated into linearly polarized light having a specific polarization direction, and then transmitted to the first Polarizing plate 130.

On the other hand, as shown in FIG. 1, in this embodiment, the first polarizing plate 130 is located on the sensing element 150, and the optical structure layer 140 is located between the sensing element 150 and the first polarizing plate 130. More specifically, as shown in FIG. 1, in this embodiment, the sensing element 150 has a sensing surface SS, the optical structure layer 140 has a plurality of oblique through holes 141, and each oblique through hole 141 and the sensor There is a first included angle θ1 between the normal vectors N of the measurement surface SS. For example, in this embodiment, the magnitude of the first included angle θ1 is approximately within a range of Brewster angle θb ± 10 degrees of the first light beam L1 incident on the first surface S1. More preferably, in this embodiment, the first included angle θ1 is equal to the Brewster angle θb of the first light beam L1 incident on the first surface S1. It should be noted that the numerical ranges herein are only for illustrative purposes, and are not intended to limit the present invention.

In this way, the oblique through hole 141 and the first polarizing plate 130 can filter the incident first light beam L1. For example, as shown in FIG. 1, in this embodiment, the configuration of the oblique through hole 141 will enable only the first light beam L1 with a specific incident angle (ie, the first included angle θ1) to be incident on the sensing element obliquely 150. Moreover, since this specific incident angle is also set as the Brewster angle θb of the first light beam L1 reflected by the light emitted by the light source 110 by the interface of other components above (ie, the first surface S1). In this way, the first light beam L1 that is incident on the first surface S1 at the first included angle θ1 and transmitted to the oblique through hole 141 and the first polarizing plate 130 can be adjusted to have a second polarization direction. Moreover, in this embodiment, the first polarizing plate 130 can be configured to pass light having a first polarization direction, wherein the first polarization direction is orthogonal to the second polarization direction, and the first light beam can be L1 is filtered.

That is, as shown in FIG. 1, in this embodiment, in the above configuration, the oblique through hole 141 can filter the first light beam L1 incident at an angle other than the first included angle θ1, and the first The polarizing plate 130 filters the first light beam L1 incident at the first included angle θ1. In this way, these first light beams L1 reflected by the interface of other components above (ie, the first surface S1) can be filtered out.

Meanwhile, as shown in FIG. 1, in this embodiment, the second light beam L2 provided by the light source 110 passes through the first surface S1 of the second polarizer 121 of the light guide module 120 and is transmitted to An object O contacting the cover 122 is reflected. For example, in this embodiment, the object O contacting the cover 122 is, for example, a finger, and the second light beam L2 reflected by the object O will carry relevant fingerprint image information.

For example, in this embodiment, the second polarizer 121 is a circular polarizer. As shown in FIG. 1, in this embodiment, the second polarizing plate 121 may include a linear polarizing plate 121 a and a quarter wave plate 121 b. In other words, in this embodiment, after the second light beam L2 reflected by the object O passes through the second polarizing plate 121, it will be modulated into circularly polarized light through the second polarizing plate 121. That is, a portion of the second light beam L2 transmitted to the first polarizing plate 130 has a first polarization direction, and another portion of the second light beam L2 has a second polarization direction, and a portion of the second light beam L2 having the first polarization direction About 50% of the total can pass through the first polarizing plate 130. In this way, the sensing element 150 recognizes the second light beam L2 reflected by the object O, and captures and outputs an image. In addition, since the noise light (that is, the first light beam L1) reflected by the interface of other components above (that is, the first surface S1) has been filtered, the signal-to-noise ratio of the image information obtained by the sensing element 150 can be reduced. Effectively enhance and produce images with good quality. For example, if the signal obtained by the traditional method is 100 and the noise is also 100, the signal-to-noise ratio (SNR) of the image information will be equal to 100/100 = 1. In contrast, although the signal obtained by the present invention is 100 * 50% = 50, when the filtering effect of the polarizer is 98%, the obtained noise value can be reduced to 100 * 2% = 2. Therefore, the signal-to-noise ratio of the available image information is 50/2 = 25, which is 25 times that of the traditional method.

FIG. 2 is a schematic diagram of another optical image sensing device according to an embodiment of the invention. The optical image sensing device 200 of FIG. 2 is similar to the optical image sensing device 100 of FIG. 1, and the differences are as follows. As shown in FIG. 2, in this embodiment, the second polarizer 221 is a linear polarizer. As such, in this embodiment, the second light beam L2 transmitted through the second polarizing plate 221 is modulated into linearly polarized light through the second polarizing plate 221. Moreover, in this embodiment, the polarization direction of the second light beam L2 may be set to have a first polarization direction after being modulated by the second polarizing plate 221. As such, the second light beam L2 transmitted to the first polarizing plate 130 can pass through the first polarizing plate 130 because it has the first polarization direction. In this way, while the noisy light (that is, the first light beam L1) is eliminated, the second light beam L2 with related fingerprint image information can also be penetrated 100%, thereby further improving the signal-to-noise ratio of the image information. And can produce good quality images. For example, if the signal obtained by the traditional method is 100 and the noise is also 100, the signal-to-noise ratio (SNR) of the image information will be equal to 100/100 = 1. In contrast, the signal obtained by the present invention is 100 * 100% = 100, but when the filtering effect of the polarizer is 98%, the obtained noise value can be reduced to 100 * 2% = 2. Therefore, the signal-to-noise ratio of the available image information is 100/2 = 50, which is 50 times that of the traditional method.

In summary, the optical image sensing device according to the embodiment of the present invention uses oblique through-holes and the configuration of the light guide module so that light with noise can be incident on the sensor obliquely only at a specific incident angle. The light above the element and having this specific incident angle is linearly polarized light having a specific polarization direction. In this way, the optical image sensing device can filter the light with noise in this part by the configuration of the first polarizer, thereby improving the signal-to-noise ratio of the image information, and can produce a good quality image.

Although the present invention has been disclosed as above with the examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make some modifications and retouching without departing from the spirit and scope of the present invention. The protection scope of the present invention shall be determined by the scope of the attached patent application.

100, 200‧‧‧ optical image sensing device

110‧‧‧light source

111‧‧‧ substrate

112‧‧‧Light-emitting element

113‧‧‧protective layer

114‧‧‧Packaging frame adhesive

120‧‧‧light guide module

121, 221‧‧‧ second polarizer

121a‧‧‧ Linear Polarizer

121b‧‧‧ quarter wave plate

122‧‧‧ Lid

130‧‧‧first polarizer

140‧‧‧ Optical Structure Layer

141‧‧‧ oblique through hole

150‧‧‧sensing element

L‧‧‧ Beam

L1‧‧‧First Beam

L2‧‧‧Second Beam

N‧‧‧ normal vector

O‧‧‧ Object

SS‧‧‧Sensing surface

S1‧‧‧First surface

VD‧‧‧Gap

θ1‧‧‧First angle

θb‧‧‧Brewster Point

FIG. 1 is a schematic diagram of an optical image sensing device according to an embodiment of the invention. FIG. 2 is a schematic diagram of another optical image sensing device according to an embodiment of the invention.

Claims (8)

An optical image sensing device includes: a light source adapted to provide a plurality of light beams, and the light beams include a first light beam; a first polarizing plate adapted to pass light having a first polarization direction; The sensing element has a sensing surface, wherein the first polarizing plate is located on the sensing element; an optical structure layer is located between the sensing element and the first polarizing plate, wherein the optical structure layer has a plurality of oblique To the through hole, and each of the oblique through holes and a normal vector of the sensing surface has a first angle; and a light guide module is located on the transmission path of the first light beam, wherein the light guide module A first surface is provided, the first light beam is reflected by the first surface and transmitted to the first polarizer, and the first light beam incident on the first surface at the first angle is modulated to have a second polarization Direction, the second polarization direction is orthogonal to the first polarization direction. The optical image sensing device according to item 1 of the patent application scope, wherein the light guide module includes: a second polarizer located on a transmission path of the first light beam, wherein the second polarizer faces the first The surface of the polarizer is the first surface; a cover is located on the second polarizer. The optical image sensing device according to item 2 of the scope of patent application, wherein the light beams further include a second light beam, the second light beam is transmitted to an object contacting the cover body and is reflected, and the sensing element The second light beam reflected by the object is identified. The optical image sensing device according to item 3 of the patent application, wherein the second polarizer is a circular polarizer. The optical image sensing device according to item 4 of the patent application scope, wherein after the second light beam is modulated by the second polarizer, a portion of the second light beam that is transmitted to the first polarizer has the first polarization Direction, and the second light beam transmitted to another part of the first polarizer has the second polarization direction. The optical image sensing device according to item 3 of the patent application scope, wherein the second polarizer is a linear polarizer. According to the optical image sensing device described in item 6 of the patent application scope, after the second light beam is modulated by the second polarizer, the second light beam transmitted to the first polarizer has the first polarization direction. The optical image sensing device according to item 1 of the application, wherein the first included angle is equal to the Brewster angle of the first light beam incident on the first surface.